228. The radioactivity of potassium prepared from animal tissue

The Radioactivity of Potassium From Human Sources

“…Our results seem to be consistent with this theory but it appears that Lasnitzki and Brewer should have found an abnormally low content of heavy isotopes in the tissue instead of the predominantly normal values which they reported. It is not, therefore altogether easy to reconcile our findings with all of those of Lasnitzki and Brewer (1941) although strictly there is no direct factual conflict. SUMMARY A comparison of the radioactivity of potassium from human and commercial sources indicates that the radioactive isotope K 4° is probably 1 or 2 per cent less abundant in human potassium.…”

“…The work was begun on account of the statement of Ernst (1934) based on an inadequate photographic method that K 4° is (relative to K 39) more abundant in living cells. Since the work was begun other papers by Pohlmann (1938), Pohlmann andNetter (1938), Lasnitzki and Oeser (1937), and by A. Lasnitzki (1939) have appeared, all concluding that if K 4° is more abundant in biological potassium the difference is not over 5 per cent.…”

“…Since more data are desirable to improve the precision of the result it seems worth while to publish our data. Moreover, since our experiments were completed, Lasnitzki and Brewer (1941) have investigated the abundance of K ~ in potassium from various sources and have found it abnormally abundant in bone (including the marrow) and in plasma but normal in other tissues except tumors where it was low. Presumably similar but smaller differences should be found for the radioactive isotope K 4°.…”